Allergies and asthma: They often occur together

Allergies and asthma: A Mayo Clinic specialist explains the connection, and what you can do to prevent attacks and manage symptoms.
By Mayo Clinic Staff

You may wonder what allergies and asthma have in common besides making you miserable. A lot, as it turns out. Allergies and asthma often occur together.

The same substances that trigger your hay fever symptoms may also cause asthma signs and symptoms, such as shortness of breath, wheezing and chest tightness. This is called allergic asthma or allergy-induced asthma. Certain substances, such as pollen, dust mites and pet dander, are common triggers. In some people, skin or food allergies can cause asthma symptoms.

James T C Li, M.D., Ph.D., a Mayo Clinic allergy specialist, answers questions about the link between allergies and asthma.

How does an allergic reaction cause asthma symptoms?

An allergic response occurs when immune system proteins (antibodies) mistakenly identify a harmless substance, such as tree pollen, as an invader. In an attempt to protect your body from the substance, antibodies bind to the allergen. The chemicals released by your immune system lead to allergy signs and symptoms, such as nasal congestion, runny nose, itchy eyes or skin reactions. For some people, this same reaction also affects the lungs and airways, leading to asthma symptoms.

Are allergies and asthma treated differently?

Most treatments are designed to treat either asthma or allergies. But a few treatments help with both conditions, for example:

Leukotriene modifier. Montelukast (Singulair) is a medication that eases both allergy and asthma symptoms. Called a leukotriene modifier, this taken-daily pill helps control immune system chemicals released during an allergic reaction. In rare cases, this and other leukotriene modifiers have been linked to psychological reactions, including suicidal thinking. Seek medical advice right away for any unusual psychological reaction to one of these medications.

Allergy shots (immunotherapy). Allergy shots can help treat asthma by gradually reducing your immune system response to certain allergy triggers. Immunotherapy involves getting regular injections of a tiny amount of the allergens that trigger your symptoms. Your immune system builds up a tolerance to the allergens over time, and your allergic reactions diminish. In turn, asthma symptoms decrease as well. This treatment generally requires regular injections over a period of three to five years.

Anti-immunoglobulin E (IgE) therapy. When you have an allergy, your immune system mistakenly identifies a specific substance as something harmful and releases antibodies, known as IgE, against the culprit allergen. The next time you encounter that allergen, the IgE antibodies sense it and signal your immune system to release a chemical called histamine, as well as other chemicals, into your bloodstream. The medication omalizumab (Xolair) interferes with IgE in the body and helps prevent the allergic reaction that triggers asthma symptoms.

You may need other medications to treat allergies or asthma, especially if your symptoms become severe at times. However, recognizing and avoiding the allergic substances that trigger your symptoms is the most important step you can take.

Tan RA, et al. The relationship of rhinitis and asthma, sinusitis, food allergy, and eczema. Immunology and Allergy Clinics of North America. 2011;31:481.

National asthma education and prevention program expert panel report 3: Guidelines for the diagnosis and management of asthma. National Institutes of Health. http://www.nhlbi.nih.gov/guidelines/asthma/asthsumm.pdf. Accessed Nov. 27, 2012.

Guidelines for the diagnosis and management of food allergy in the United States: Summary of the NIAID sponsored expert panel report. Bethesda, Md.: National Institute of Allergy and Infectious Diseases. http://www.niaid.nih.gov/topics/foodallergy/clinical/Pages/default.aspx. Accessed Dec. 5, 2012.

What is food allergy? National Institute of Allergy and Infectious Diseases. http://www.niaid.nih.gov/topics/foodAllergy/understanding/Pages/whatIsIt.aspx. Accessed Dec. 5, 2012.

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